Air conditioning



May 3, 1949.

Filed Dec. 22. 1945 s. w. E. ANDERSSON 2,469,142

AIR CONDITIONING 2 Sheets-Sheet 1 v INVENTOR. 54w Mam y 1949. s. w. E. ANDERSSON 2,469,142

AIR CONDITIONING Filed Dec. 22, 1945 2 Sheets-Sheet 2 ark- Patented May 3, 1949 AIR CONDITIONING Sven W. E. Andersson, Evansville, Ind., assignor to Serve], Inc., New York, N. Y., a corporation of Delaware Application December 22, 1945, Serial No. 636,977

12 Claims.

The present invention relates to a control system for an all year air conditioning unit. More particularly the invention relatestoimprovements in a control system of the type illustrated and described in my prior U. S. Letters Patent No. 2,381,427 dated August 7, 1945, entitled Air conditioning.

The air conditioning unit illustrated in my prior patent comprises a heating system having a heating element, a heat operated refrigeration system having a cooling element, a single source of heat to operate the heating system or heat operated refrigeration system, and a blower for circulating air to be conditioned over the heating and cooling elements. The control for the air conditioning unit comprises electric circuits and a switch box in the enclosure to be conditioned having one switch to select the heating system circuits for operation, a second switch for selecting the heat operated refrigeration system circuits for operation, and a third switch to select the blower circuit for operation independently of the heating or cooling system. If the first switch is actuated the heating system and blower will be operated concurrently when a room thermostat calls for heating and if the second switch is actuated the refrigeration system and blower will be operated concurrently when the room thermostat calls for cooling.

One of the objects of the present invention is to provide a control for an air conditioning unit of the type indicated with a single double throw switch to.select the heating system circuits for operation in one position, select the refrigera- 'tion circuits for operation in another position and open the circuits at an intermediate position.

Another object is to provide a control of the type indicated having a thermostatically operated switch means cooperating with the double throw selector switch to complete circuits for initiiating operation of the refrigeration system upon a rise in temperature and complete circuits for initiating operation of the heating system upon a fall in temperature.

Another object is to provide an electric control of the type indicated for initiating the operation of a plurality of heating burners in the same sequence when either the heating orrefrigeration system is selected for operation.

Another object is to provide an electric control of the type indicated which is operable to delay the operation of the blower until the heating element is hot when the heating system is selected for operation.

Another object is to provide an electric control for an air conditioning unit of the type indicated which is operable to simultaneously initiate operation of the refrigeration system and blower when the refrigeration system is selected for operation and delay operation of the blower until the heating element is hot when the heating system is selected for operation.

Another object is to provide an electric control for an air conditioning unit of the type indicated which is operable to delay the supply oi. cooling water to the refrigeration system until heating medium has been supplied thereto.

Another object is to provide an electric control of the type indicated for delaying operation of the blower when the heating system is selected for operation and for delaying the supply of cooling water to the refrigeration system when the refrigeration system is selected for operation.

Still another object is to'provide an electric control of the type indicated having a relatively compact construction and arrangement of operative elements and adapted for eas service and repair.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout the several views. In the drawings:

Fig. l is a diagrammatical view of an air. conditioning unit showing the elements to be con- .trolled by the control system, and

Fig. 2 is a wiring diagram of the electrlc'control system for the air conditioning unit.

Referring to the drawings, Fig. 1 illustrates an enclosure 5 to be conditioned and an air conditioning unit comprising a conduit 6 for receiving air from the enclosure and a conduit 1 for delivering air to the enclosure. It is to be understood that in an actual installation the conduits will be arranged in a difierent manner from that herein shown and that provisions may be made to supply fresh air to the air recirculated through the enclosure 5 and the conduits 6 and l. The air to be conditioned is circulatedthrough the conduits 6 and l in the direction indicated by the arrows by means of a blower 8. As the air flows through the conduit 6 it is conditioned by elements mounted therein comprising a filter 9, a cooling element ill, a heating element II, and a humidifier I2. The cooling element Ill constitutes the evaporator'of a heat operated absorption refrigeration system while the heating element ll constitutes the radiator of a steam heating system. Both the refrigeration system and the heating system are selectively supplied with steam from a boiler l3 con- Suiiice it to state herein that the refrigeration' system comprises a generator I5, a condenser I6, evaporator l0, absorbed I1 and heat exchanger I8, interconnected to provide a closed circuit. The generator I5 has a series of upright tubes I9 connected at their lower end to an inlet chamber 20 for absorption solution and connected at their upper ends to a separting chamber 2|. Surrounding the tubes I9 is a shell 22 providing a heating chamber 23 therebetween. Separting chamber 2| is connected to the condenser It by a conduit 24 and the condenser, in turn, is connected to the evaporator I by a depending U-shaped conduit .25. The evaporator l0 communicates with the absorber l1 through passages or headers 32 in the manner illustrated and described in detail in the Thomas patent referred to above. Absorption solution weak in refrigerant, or in other words, a concentrated salt solution flows from the separating chamber 2| to the top of absorber I'l in a path of flow including the conduit 26, heatexchanger I8, and conduit 21. Absorption solution strong in refrigerant or, in other words, dilute salt solution flows from the bottom of the absorber I! to the inlet chamber 20' at the bottom of the generator I in a path of new including the conduit 28, heat exchanger I6 and conduit 29.

Steam is supplied from the boiler I3 to the heating chamber 23 of the generator l5 through a conduit 30. A vent tube 3| is connected at one end to the heating chamber 23 of the generator I5 adjacent the top thereof and the other end of the vent tube is opened to the atmosphere so that steam will be supplied to the generator at atmospheric pressure. If all of the steam supplied to the generator I5 is not condensed in the heating chamber 23 due to faulty heat transfer through the tubes I9 resulting from scale or the like, steam will escape through the vent tube 3|.

The absorber I I and condenser l6 are cooled by cooling water from any suitable source such as the cooling tower 33 illustrated in the drawings. The cooling tower 33 may be of any suitable construction wherein a stream of water descends by gravity through the tower simultaneously with the flow of a stream of air upwardly through the tower in direct contact therewith to evaporate a portion of the water and reduce its temperature by the removal of the heat of vaporization. An electric motor driven fan 34 is provided adjacent the upper end of the cooling tower 33 to induce a flow of air upwardly therethrough and an electric motor driven pump 35 is provided at the bottomof the tower to circulate cooled 'water through the absorber I1 and condenser I6 of the refrigeration system. For this latter purpose a conduit 36 connects the pump 35 to the bottom of a series of cooling coils 31 in the absorber H. The cooling water discharged from the top of the cooling coils 31 in the absorber I'I flows through a conduit 38 to the condenser 6 and then from the condenser 4 I6 through the conduit 38 back to the top of the cooling tower 33.

When stea'm'is supplied to the heating chamber 23 of the generator I5 the refrigerant, water; is vaporized from absorption solution in the tubes I9 by heat transferred through the walls thereof. As the refrigerant vapor risesin the tubes I9, it raises absorption solution into the separating chamber 2| by vapor lift action. The absorption solution in the separating chamber 2| flows to the top of the absorber through the conduit 26, heat exchanger I8 and conduit 21. The refrigerant vapor flows from the separating chamber 2| through the conduit 24 to the condenser I6 where it is liquefied by the transfer of its heat of vaporization to the cooling medium from the cooling tower 33. The liquid refrigerant flows by gravity from the condenser I6 into the U-shaped conduit 25 and from the latter into the evaporator Ill. Due to the absorption of the evaporator I0. At this low pressure the refrigerant, water, evaporates at a low temperature of 45 F. to 50 F. as it flows through the evaporator I 0. As the heat for vaporizing the refrigerant is supplied from the ambient, a refrigeratin eifect is produced. The absorption solution in the absorber l1, enriched with the refrigerant vapor absorbed therein, flows back to the inlet chamber 20 of the generator I5 through the conduit 28, heat exchanger I8 and conduit 29 to complete the cyclic paths of flow for the refrigerant and absorbent. The pressure differential in the system is maintained by a column of liquid refrigerant in the U-shaped conduit 25 constituting a liquid trap and liquid columns in the conduits 21 and 28 between the generator I5 and absorber I I. For purposes of illustration the liquid levels in the conduits 25, 26 and 28 are indicated by the reference characters 3:, y and z. Y As shown diagrammatically in Fig. 1, alow temperature cut-out switch 40 is provided for interrupting the operation of the refrigeration system if the temperature in the evaporator I0 falls below a predetermined value. The switch 40 is normally closed and operated to open position bya thermostat 4| responsive to the temperature of the refrigerant in the evaporator ID. The thermostat may be of any suitable construction and as illustrated comprises a bulb 42 positioned in a well in the evaporator .I II and connected to a bellows 43 by a capillary tube 44. The

bellows 43 contains vapor which condenses in the bulb 42 when the temperature in the evaporator is too low to contract the bellows and the latter is connected to the movable contact of the low temperature cut-out switch 40.

Theheating system comprises the radiator II and a conduit 45 connecting the radiator to the boiler I3. The radiator II has division walls 46 therein to cause the heating steam to successively pass through different sections of the radiator in series. A vent pipe 41 connects the end of the last section of the radiator II with the vent pipe 3| so that steam is supplied to the radiator at atmospheric pressure. All of the steam supplied to the radiator II condenses therein unless there is faulty heat transfer due to dirt or scale in the radiator or a dirty filter 9 andunder such'c'onditions steam will escape through the vent pipe 41 to the atmosphere. I

Steam is supplied to either the refrigeration system or heating system byvthe diverter' valve I4 comprising a valve body in the form of a -arm 52 fast on the pivot rod 5I at the outside --of the chamber 50 is connected through a link 53 to a crank arm 54 on the shaft of a two position electric motor 55. The motor 55 may be of any suitable type and as illustrated has a field winding I32, connected in series with limit switches LS and LSa, see Fig. 2, the switches being operated by the .rotor to open one or the other alternately at each half revolution of the output shaft. The arrangement of the ends of the steam pipes 30 and 45 is such that the valve element 50 will alternately close one of the steam pipes and open the other when moved from one to the other of its two positions. In the position illustrated in Fig.' 1 the valve element 50 closes the steam supply pipe 30 and opens the steam supply pipe 45 to render the heating system operative for heating.

The boiler I3 may be heated by any suitable fluid fuel burners such as the pluraility of gas burners 5B, 51 and 58 as illustrated. The flow of gas fuel to the burners 56, 51 and 58 is controlled by a master valve 59 in the fuel supply line 60 and by individual control valves BI and 62 for the burners 51 and 58. The Valves are automatically closed by suitable springs and the master valve 59 is opened by an electric motor indicated by the reference character 63 while the valves 6| and 62 are opened by individual solenoids 64 and 65. The special motor operated master valve 59 is used in the fuel supply line 60 to insure positive starting and stopping the flow of fuel to the burners. More heat is required by the heatin system to heat the air than is required by the refrigeration system to cool the air and for this purpose a gaspressure regulator 66 is provided in the fuel supply line 60. Preferably the gas pressure regulator is of the type illustrated and described in my prior U. S. Letters Patent No. 2,356,556, issued August 22, 1944, and entitled Regulator. The gas pressure regulator 66 is operated by the motor 55 through a Bowden wire 66a.

A low water cut-out unit 61 mounted on the side of the boiler I3 is adapted to open the electrical control circuit for the gas burners 56, 51 and 58 and close the circuit for a magnetically operated water valve 68 when the water level in the boiler is too low. The low water cut-out unit 61 comprises a float 69 responsive to the liquid level in the boiler I3 for holding a movable contact 10 in engagement with a fixed contact II when the level of the water in the boiler is sufilciently high and for actuating the movable contact I into engagement with a fixed contact 12 when the level of the water is too low. As

illustrated in the drawings, the contact 12 is con-' nected to the magnetically operated water valve 68 in a supply pipe 13.

Condensate from the radiator I I of the heating system drains by gravity through the steam pipe .45 back to the boiler I3. However, condensate in the heating chamber 23 of the generator I is below the water level in the boiler I3 and is returned to the boiler by an electric motor-operated condensate return pump 14. i The condensate return pump 14 is connected to the bottom of the steam chamber 23 by a conduit 15 and the outlet from the pump is connected to the boiler I3 by a conduit 16 having a portion extending upwardly above the water level in the boiler. If for any reason the condensate return pump -'l4 fails to Operate, the condensate will overflow into a chamber ll containing a thermal responsive element 18.

A normally closed thermostatically operated cut-out switch 8| cooperates with the heating and cooling systems and the condensate return pump 14. The cut-out switch 8| has a movable contact 82 engageable with a fixed contact 83 and the movable contact is connected to a thermostat bellows 84. The bellows 34, in turn, is operated by the vapor pressure of a volatile liquid in the bulb 18 in the overflow chamber 11 of the condensate return pump 14 or a bulb 85 in a chamber 86 connected in the vent pipe 3I. Thus, the escape of steam from either the radiator II of the heating system or heating chamber 23 of the refrigeration system or overflow of condensate from the pump 14 will operate the bellows 84 to open the cut-out switch 8|.

The humidifier I2 comprises a series of vertically spaced pans 8'1, a water Supply line 88 and an electromagnetically operated water valve 89. Overflow pipes in each of the pans 81 supply water to each of the successively lower pans and drains water from the lowermost pan into a suitable sump in the conduit 6. The sump is also adapted to collect condensate removed from the air by the evaporator Ill. As thus far described the air conditioning unit is substantially identical with that illustrated and described in my prior Patent No. 2,381,427 referred to above.

In accordance with the present invention a delayed action control switch 90 is provided for delaying operation of the blower 8 until the heating radiator I I is hot when the heating system is selected for operation; and for delaying operation of the cooling tower 33 and condensate return pump "until the generator is hot when the refrigeration system is selected for operation. The delayed action control switch 90 comprises fixed contacts 9I, 9Ia and 92 and a pair of movable contacts 93 and 94 connected for simultaneous operation by the expansible' bellows 95 of a thermostat. The bellows 95 is connected by capillary tubes 96 and 91 to thermosensitive bulbs 98 and 99 located in the radiator II of the heating system and steam supply pipe 30 for the generator I5 of the refrigeration system, respectively. The bulbs 98 and 99 contain a volatile liquid which is vaporized when steam is supplied to the radiator II or to the generator I5 and exerts pressure to expand the bellows 95 and operate the movable contact 93 from engagement with the fixed contact 9Ia into engagement with the contact 9I and the contact 94 into engagement with the fixed contact 92. The arrangement of the switch 90 in the control system to delay operation of the blower 8 and cooling tower 33 will appear from the following description.

The control system for the air conditioning unit including the various operating elements previously described is illustrated diagrammatically in Fig. 2 and includes a selective controller I00 in the enclosure 5 and a plurality of electric circuits. The controller I00 comprises a switch box having a four-pole double-throw switch IOI and a single-pole double-throw switch I02, see Fig.2. The four poles of the switch IOI are indicated by the reference characters, D, E, F, and G, and the three contacts for each pole are indicated by the reference character for the pole and the subscript I, 2 and 3, such as D D and D etc. The four poles are mechanically connected by a bar l03a, see Fig. 2, for simultaneous operation by a manually operable lever I03, see Fig; 1. When the four pole switch IN is in the upper position illustrated in Fig. 2 it connects certain of the branch circuits to render the heating system operative; when moved to the lower position to engage the poles D, E, F, and G with the fixed contacts D E F and G it connects certain of the branch circuits to render the refrigeration system operative; and when moved to an intermediate position it disconnects all of the branch circuits to render both the heating and cooling systems inoperative.

Switch I02 has a pole J and fixed contacts J, J, and J and thepole J is adapted to be operated manually to two positions by a lever I04, see Fig. 1. When the pole J of the switch I02 is in the upper position illustrated in Fig. 2 it connects the blower 8 for joint operation with the selected heating or refrigeration system and when moved to its lower position into engagement with the fixed contact J it connects the blower for continuous operation independently of the switch IOI.

Also mounted in the switch box of the controller I is a thermostatically operated switch means I 05 substantially identical with that illustrated in my prior Patent No. 2,381,427 referred to above. The switch means I05, illustrated diagrammatically in Fig. 2, comprises a pair of switches arranged to be actuated in sequential order in two directions of movement. One of the switches has a movable contact I06 and a pair of fixed contacts I01 and I08 at opposite sides thereof and the other switch has a movable contact I09 and a pair of fixed contacts H0 and III v positioned at its opposite sides. The movable contacts I06 and I09 are adapted to be moved in sequential order by a single thermostat illustrated diagrammatically in Fig. 2 as comprising an expansible bellows H2, a bulb II3 outside of the switch box subjected to the ambient temperature in the enclosure 5 and a capillary tube II4 connecting the bulb and bellows. The bulb II3 contains a volatile liquid which produces a vapor pressure corresponding to the temperature of the ambient to expand the bellows I I2. The switches are so arranged with respect to each other that the bellows II2 first actuates the movable contact I09 into engagement with the fixed contact III upon a predetermined rise in temperature and thereafter actuates the movable contact I06 into engagement with the fixed contact I08 upon a further predetermined rise in temperature. A spring II5 actuates the movable contacts I06 and I09 successively into engagement with the fixed contacts I01 and H0 upon a fall in the temperature of the ambient. To make the bulb II3 of the thermostat the coldest and therefore the sensitive part to changes in ambient temperature a heater is provided in the switch box comprising an electric resistance element I I6. 7

The electric control system includes line voltage circuits for energizing the motors for the blower 0, cooling tower fan 34 and pump 35 condensate return pump 14, and low voltage circuits for controlling all other elements of air conditioning unit. Electric current is supplied to the control system from the service mains, S S through a line switch I H to the primary winding of a step-clown transformer H0. The circuit for the blower 8 .is connected across the service mains S and S in parallel with the primary winding of the transformer H8 and comprises the conductor 0 connecting the line S to one side of the blower motor, a conductor I20 connecting the other side of the blower motor to a relay switch I2I and a conductor I22 connecting relay switch to the other service line S The motors for the cooling tower pump 35, cooling tower fan 34, and condensate return pump 14 are connected in parallel V 'are protected by suitable fuses.

The resistance element II6 for heating the interior of the control box for switch I00 is con nected across the terminals of the step-down transformer H8 by an electric circuit comprising a conductor T connectin one terminal of the transformer to one side of the resistance element,

a conductor I21 connecting the other side of the resistance to the fixed contact J of the switch I02 and a conductor T connecting the switch contact J to the other terminal of the trans- .former secondary. Preferably a second resistance I28 is provided in the conductor T to adjust the amount of heat produced by the heating element II6. I

The control system also includes a first branchcircuit H in parallel with the circuit for the heating resistance H6 for initiating operation of the heating system when switch IOI is in the position illustrated in Fig. 2; a, second branch circuit C in parallel with the circuit for the resistance element I I6 to initiate operation of the refrigeration system when switch I0 I. is moved to its lowermost position; and a plurality of tertiary circuits B in series.

and B to control the rate of operation of the selected system. The first branch circuit H for the heating system comprises a conductor I30 connected to the conductor T adjacent one terminal of the transformer secondary, low Water control switch 61 and vent switch 8| arranged Conductor'I3l from the switch 0| is connected to one end of'field winding I32 of the motor 55, to one side of the magnetically operated water valve 89 for humidifier I2, and to one side of the solenoid of the fuel control valve 62 forthe burner 58 in parallel arrangement. The opposite end of the motor field windin I32 is connected by a line I35 including limit switch L3 to conductor H. The opposite sides of the water valve 89 and fuel valve 65 are also connected to the conductor H which in turn, is connected to terminal F of the selector switch IOI. Pole F of switch IOI when in position to select the heating system for operation connects terminal F to terminal F and terminal F being connected to terminal E by a suitable jumper continues the circuit to the terminal E through the pole E.

. I00 engages the contact I0.'l to complete the circuit through conductors I34 and I34a to the conductor T If the refrigeration system is selected for operation by manually actuating the switch IN to engage its poles D, E, F, and G with the terminal contacts D E F and G the second branch circuit C is energizedby conductor I30, switches 61 and 8|,Lconductor I3I to one end of the field contact G of the switch IOI.

winding I32 of the motor 55. The opposite end.

The plurality of tertiary branch circuits B and B for controlling the rate of operation of the selected heating or refrigeration system comprises the conductor I30, switches 61, 'BI and low temperature cut-out switch 40. A conductor I31 connects switch 40 to one side of the motor 63 for operating the master fuel valve 59 and conductor B connects the opposite side of the valve motor 63 to the terminal contacts E of the switch IOI. When the switch IOI is moved to its upper position illustrated in Fig. 2 to select the heating system for operation a circuit is completed through the pole E, conductor I33, switch contacts I01 and I06 of the'switch means I05 and conductors I34, I3'4a and T When the switch IN is moved to its lowermost position to select the refrigeration system for operation, the circuit is completed through the pole E of the switch IOI, conductor I38, contacts III and I09 of the switch means I05 and conductors I34, I34a and T The branch circuit B includes a conductor I39 connecting the conductor I31 to one side of the solenoid 64 for the fuel valve 6|. The opposite side of the solenoid 64 is connected by conductor 18 to the terminal contact D of the switch IOI. When the switch IOI is moved to select the heat ing system for operation the circuit is completed through the pole D, contact terminal D conductor I40, contacts H and I09 of the switch means I and conductors I34, I34a, and T When the switch IOI is moved to select the refrigeration system for operation the circuit is completed through the pole D, conductor I4I, contacts I08 and I06 of the switch means I05 and conductors I 34, I34a and T As illustrated in Fig. 2 a plurality of safety switches or pilotstats I42 and I43 are provided in the conductor B which are operated by suitable thermostats or the like to open the circuit forthe master fuel valve 63 if the pilots for igniting the fuel are extinguished.

The blower 8 is adapted for operation jointly with the selected heating system or refrigeration system or is adapted for operation independently of the heating and refrigeration systems. The branch or ventilating circuit V comprises a relay coil I45 for operating the relay switch I2I in the line circuit as previously described. -When the heating system is selected for operation by the switch IOI, the circuit for the relay coil I45 comprises a conductor I46 connected between the terminal conductor T of the transformer secondary and. relay coil. The opposite end of the relay coil I45 is connected to the movable contact 93 of the delayed actioncontrol switch 90. The circuit is completed by a conductor I4'I connecting the fixed contact 9I of the delayed action control switch 90 to the other terminal conductor T of the transformer secondary. As the movable contact 93 of the delayed action control switch 90 is only operated into engagement with the fixed contact 9I when steam has been supplied to the radiator II, the operation of the blower 8 is independent of the operation of the burners 56, 5'! and 58 and is delayed until the heating radiator II is hot.

When the refrigeration system is selected for operation by moving the switch IOI to engage the poles D, E, F, and. G with fixed contacts D E 10 P and G energization of the relay coil I45 is controlled by the thermostatically operated switch means I05 by a circuit including the conductor I46, relay coil I45, contacts 93, 9Ia of delayed action switch and conductor V connected to the terminal contact J of the switch I02. With the pole J of the switch I02 in engagement with the fixed contact J the circuit is completed through the conductor I49 connecting fixed con tact J to fixed contact F of the switch IOI, poles F and E connected by a jumper, conductor I38, contacts III and I09 of the switch means I06 and conductors I34, I34a, and T In this way the relay coil I45 is immediately energized to cause simultaneous operation of the blower 0 with the burner 56 when the thermostat switch means I05 calls for cooling. When steam is supplied to the heating chamber 23 of the generator I5 the thermostatic bulb 99 will be heated and will operate through the bellows9-5 to engage the movable contact 93 with the fixed contact 9| of the delayed action control switch 90 to complete the circuit directly through conductor I41, However, such shifting of circuits will not interrupt the operation of the blower 8.

' When ventilation is desired without heating or cooling, selector switch IOI is moved to its inter- With the selector switch IOI at its lowermost position to select the refrigeration system for operation, the pump 35 and fan 34'for the cooling tower 33 and the condensate return pump I4 will be brought into operation but their operation will be delayed until steam is supplied to the heating chamber 23 of the generator I5. For this purpose a circuit is provided from the conductor I31 through a switch I50 on the motor 63 for the fuel valve 59 and a conductor I5I to one side of a relay coil I52 for operating the relay switch I25. The opposite side of the relay coil I52 is connected by a conductor I53 to the movable contact 94 of the delayed action switch 90. When steam has been supplied to the heating chamber 23 of the generator I5 of the refrigeration system bulb 99 will be heated to expand bellows 95 to engage the movable contact 94 of the delayed action switch 90 with the fixed contact 92 to complete a circuit through conductor I54 connected to the conductor C, contact G and pole G of the selector switch IOI, and conductors I36, I340, and T The switch I50 is operated by the motor 63 for the master fuel valve 59 and is closed whenever the valve is open and is opened whenever the valve is closed. Thus, operation of the cooling tower 33 and condensate return pump I4 is delayed until steam is supplied to the generator I5 but their operation is stopped when the fuel 1 to the burners is shut off by the master valve 59.

A switch I55 is connected to short circuit the low temperature cut-out switch 40 when the heating system is in operation to prevent a low temperature in the evaporator II in the Winter time from interfering with the operation of the heating system. The switch I55 is operated to closed position by the motor 55 when the heating system is selected for operation and to open position when the refrigeration system is selected for operation. A preferred embodiment of the invention operating the fuel valve 6|.

' tem for operation as illustrated in Fig. 2. It is also assumed that the temperature of the air in the enclosure is sufiiciently low so as to have caused the movable'contact I06 of the switch means I 05 to be engaged with the fixed contact I01 under the control of the room thermostat I I2, H3, H4 and spring II5. Under these conditions the branch circuit His energized and has caused operation of themotor 55 to the po.- sition shown in Fig. 1 and thereby operated the diverter valve I4 to open the steam supply pipe 45 to the radiator II and close the supply pipe 30 to the generator I5; operated the gas pressure regulator 66 through the Bowden wire 66a to adjust the rate of fuel flow for heating; and opened limit switch LS to stop the motor, closed switches Isa and I55 to set the motor for its next cycle of operation and short circuited the low temperature cut-out switch 40, respectively. The energization of the branch circuitvH has also energized the solenoids 89 and 65 to open the water supply valve for the humidifier I2 and fuel valve 62 for the burner 58. I

The branch circuit B is also energized which has caused operation of the electric motor 63 to However, it is further assumed that burners 56 and 58 have not been operating for a sufficiently long period of time to generated steam so that the blower 8 is inoperative.

When steam is generated in the boiler I3 it will flow through the diverter'valve I4 and supply pipe to the radiator I I. Steam in the radiator II will heat the thermostat bulb 98 and expand the bellows 95 to engage the movable contact 93 of the delayed action control switch 90 with the fixed contact 9 I see Fig. 2, and thereby energize the relay coil I45. Energization of the relay coil I45 will close the relay switch I 2| and energize the line circuit including the motor for the blower 8 connected across the supply mains S and S Operation of the blower 8 will cause air to be drawn from the enclosure 5 into the conduit 6 and through the filter 9, radiator I I, and humidifier I2. Asthe air passes through the radiator II and humidifier I2 it will be heated and humidified and delivered by the blower 8 to the enclosure 5 through the conduit 1. By delaying operation of the blower 8 -until I to decrease the bellows H2 and spring II5 of the room thermostat will actuate the movable contact I09 of the switch means I05 into engagement with the fixed contact IIO to energize the branch circuit B including the solenoid 64 for Upon energization of the solenoid 64 fuel valve 6| will open to supply fuel to the burner 51 .to increase the amount of heat supplied to the boiler I3 and the rate of steam generation therein.

As the temperature of the air in the enclosure 5 increases predetermined increments, the movable contacts I09 and I06 will be moved by the.

' l2 room thermostat continues to operate the switch means I05 in response to changes in the room temperature to operate the heating system intermittently with a step control to vary the rate of heating in accordance with requirements. v

If the level of the water in the boiler I3 falls too low the contact I0 of the low water cut-out switch 61 will be actuated, by the float 69 out of engagement with the contact II to open the branch circuits H, B and B and into engagement with the contact 12 to close the circuit,

through the solenoid of the water valve '68 to open the latter and supply make-up water to the boiler I3. When the Water level in the boiler I3 rises to the proper level by the addition of makeup water thereto, float 69 will actuate the contact I0 into engagement with the contact II to again complete the branch circuits H, B and B. Also if steam escapes through the vent pipe, 41 from the radiator II the vent switch 8I will be opened by the thermostat '84, 85 to deenergize the branch circuits H, B and B and the vent switch will close to again energize the branch circuits H, B and B when steam ceases to flow through the vent pipe.

To adjust the air conditioning unit for summer conditions the selector switch IOI is moved from the position illustrated in Fig. 2 to its opposite or lowermost position to select the refrigeration system for operation by engaging the poles D, E; F, and G with the fixed contacts 'D r i, 1

and G Immediately upon operation of the selector switch IN the branch circuitv C is energized including the field winding I32 of the motor 55. Energization of the winding I32'will cause. the motor to rotate through 180 and thereby the switch I55, see Fig. 2. When the temperature in the enclosure 5 rises to a predetermined value,

movable contact I09 will be operated into engage- ,ment with the fixed. contact III of the switch means I05 by the room thermostat H2, H3 and H4. Closing of the contacts I09 and III will energize the branch circuit B including the electric motor 63 to open the master fuel valve 59 and close the switch I50. Fuel is then supplied to the burner 56 to heat the boiler I3.

Closing of the contacts I09 and III of the switch means I05 also energizes the branch circuit V including the relay coil I45. Relay switch I2I then will close to energize the line circuit for the blower 8. Thus the blower 8 is operated simultaneously with the operation of the burner 56 to cause air to be circulated through the enclosure 5 and conduits 6 and 1 of the air conditioning unit. The circulation of air in the enclosure 5 whether or not the air is cooled by, the evaporator I0 gives the occupants of the enclosure the efiect of being cooler due to the movement of the air.

When steam is generated in the boiler I3 it will flow through the diverter valve I4 and supply pipe 30 to the generator I5 to initiate operation of the refrigeration system and the evaporation of refrigerant in the evaporator I0'will cool and dehumidify the air passing therethrough. Should the temperature of the enclosure con.- tinue to rise the contact I06 of the switch means I05 will be moved into engagement with the fixed contact I08 by the room thermostat H2, H3, II4

to energize the branch circuit B including the solenoid 64 for the fuel valve GI. Upon energization of the solenoid 64 the fuel valve 5| will be opened to cause operation of the burner 51 and thereby increase the rate of steam generation and the rate of operation of the refrigeration system to cool the air circulated by the blower 8. Upon a decrease in the temperature of the enclosure 5 the movable contacts I09 and I06 of the switch means I05 will be moved successively by the room thermostat I I2, I I3, I I4 to open the branch circuits B and B to first decrease the rate of operation of the refrigeration system and thereafter discontinue its operation. Thus the refrigeration system is operated intermittently in response to variations in the temperature of the enclosure to maintain its temperature within a predetermined range.

When heating steam is supplied to the generator I5 the thermostat bulb 99 will be heated and thereby expand the bellows 95 to actuat the switch contacts 93 and 94 of the delayed action switch I09 into engagement with the fixed contacts 9| and 92. The closing of the contacts 9| and 93 merely shifts the circuit for energize ing the relay coil I45 without interrupting the operation of the blower 8. Engagement of the contact 94 with the contact 92 of the delayed action control switch 90, however, completes a circuit through the relay coil I52 to close the relay switch I25. Closing of th relay switch I25 will energize the line circuit including the motors for the cooling tower fan 34, cooling tower pump 35, and condensate return pump I4. It will be observed, therefore,'that the control system of the present invention delays the operation of the cooling tower 33 and condensate return pump 14 until operation of the refrigeration system has been initiated by supplying steam to the generator I5. The reason for the delayed operation of the cooling tower is to prevent cooling down the absorber I1 and condenser I6 before refrigerant vapor is xpelled in the generator I5 which might cause operation of the low-temperature cut-out switch 40 when refrigerant is first introduced into the evaporator I if the cooling water is especially cold. The condensate return pump I4 will withdraw condensate from the bottom of the heating chamber 23 of the generator I and return it to the boiler I3. When the room thermostat operates the switch means I05 to discontinue operation of the refrigeration system, the branch circuit B will be deenergized and the master fuel valve 59 will close-and open the switch I50. Upon opening of the switch I50 the circuit for the relay coil I52 is open whereby the relay switch I25 opens to discontinue operation of the. motors for the cooling tower fan 34, cooling tower pump 35, and condensate return pump 14. Thus, the operation of the cooling tower 33 and condensate return pump 14 are delayed until heating s eam is sup-. plied to generator I5 to prevent excessive initial cooling of the absorber I1 and condenser I5 but the operation of the cooling tower and condensate pump is discontinued simultaneously with the shutting off of fuel to the boiler I3 to prevent excessive concentration of solution in the generator after pumping stops. However, due to interlocking arrangement of the switch I50 with the master fuel valve 63 cooling water will continue to be delivered by the cooling tower circulating pump 35 if the master fuel valve fails to close.

. If for any reason the temperaturein the evaping operation of the refrigeration system, the low temperature cut-out switch 40 will be operated to stop the operation of the refrigeration system. When the temperature of the evaporator again rises above a predetermined low value the operation of the refrigeration system will again be initiated. Also the operation of the refrigeration system will be interrupted if steam escapes through the vent pipe 3I by opening the vent switch BI as previously described.

It is many times desirable especially in the spring and fall seasons to operate the blower 8 independently of the heating and refrigeration syst, to ventilate the enclosure 5. For this purp se-the switch IOI will be moved to a central or neutral position and the switch I02 manually operated to engage the pole J with the fixed contact J The branch circuit V including the relay coil I45 then will be energized independently of the branch circuits H, C, B and B Upon energization of the relay coil I45 the relay switch I2I will be closed to energize the line circuit in cluding the blower 8. Operation of the blower 0 will cause circulation of air in the enclosure 5 and conduits 6 and I of the air conditioning unit under the control of the manual switch I05.

It now will be observed that the present invention provides a control system for an air conditioning unit having a single double-throw switch for manually selecting the heating system for operation when moved to one of its two positions and selecting the refrigeration system for operation when moved to the other of its two positions. It also will be observed that the control system operates automatically to control the selected system to maintain a predetermined temperature in the enclosure. It further will be observed that the control system delays operation of the blower until the radiator ishot when the heating system is selected for operation and delays operation of the cooling water supply means and condensate return pump until the generator is hot when the refrigeration system is selected for operation.

While a preferred embodiment of the invention is illustrated and described herein, it is to be understood that modifications may be made in the control system and in the construction and arrangement of the parts of the air conditioner to be controlled without departing from the spirit or scope of the invention.

What is claimed is:

1. An air conditioning unit comprising a heating system having a heating element, a refrigeration system having a heated element and a cooling element, a blower for circulating air to be conditioned over the heating and cooling elements, means for supplying cooling water to the refrigeration system, a control having means for selecting the heating system or refrigeration system for operation, and a devic cooperating with said selective means for delaying operationof the blower until the heating element is hot when the heating system is selected for operation and delaying operation of th cooling water supply means until the heated element is hot when the refrigeration system is selected for operation.

2.v An air conditioning unit comprising a heating system having a heating element. a refrigeration system having a heated element and a cooling element, a blower for circulating air-to be conditioned over the heating and cooling ele-. ments, a cooling tower for supplying cooling water 15 to the refrigeration system, and a control having means for selecting the heating system or refrigeration system for operation, an element responsive to the temperature of the air to be con-' ditioned for regulating the operation ofv the selected heating or refrigeration system, and a device responsive to the temperature of the heating system having a heating element, a heat operated refrigeration system having a generator and a cooling element, a blower for circulating air to be conditioned over the heating and cooling elements, means for supplying cooling water to the refrigeration system, a boiler for supplying a heating medium to the heating system or heat operated refrigeration system, and a, control including means for selecting the heating system or refrigeration system for operation, an element responsive to the temperature of the air to be conditioned for controlling the operation of the boiler, and a thermostat responsive to the temperature of the heating element and generator for delaying operationof the blower until the heating element is hot when the heating system is selected for operation and delaying operation of the cooling water supply means until-the generator is hot when the refrigeration system is selected for operation.

4. An air conditioning unit comprising a heating systemhaving a heating element, a heat operated refrigeration system having a generator and a cooling element, a blower for circulating air to be conditioned over the heating and cooling elements, a cooling tower for supplying cooling water to the refrigeration system, a boiler for supplying a heating medium to the heating and refrigeration systems, fuel burners for heating the boiler,

and a control including means for selecting the heating system or refrigeration system for operation, an element responsive to the temperature of the air to be conditioned for controlling the operation of the fuel burners, and a thermostat responsive to the temperature of the heating element and generator for delaying operation of the blower until the heating element is hot when the heating system is selected for operation and delaying operation of the cooling tower until the generator is hot when the refrigeration system is selected for operation.

5. In an airconditioning unit, a heating system having a heating element, a heat operated refrigeration system having a cooling element, an electric control-circuit having a branch for selecting the heating system for operation, a branch for selecting the refrigeration system for operation and branches for initiating operation of the selected system, a double throw switch in said cir cuit operative at one of its two positions to connectthe branches controlling the heating system branch when moved in the other direction, and a thermostat responsive to the temperature of the Toperation of the selected system.

16 r air to be conditioned for operating the second switch to initiate operationof the selected system.

6. In an air conditioning system, a heating system having a heating element, a heat operated refrigeration system having a cooling element,-a single source of heat, an, electric control circuit having a selecting branch operative when energized to direct heat from said source to the heat-- ing system, a selecting .branch operative when energized to direct heat from said source to the heat operated refrigeration system and regulating branches operative when energized to supply heat, a manually operable double throw switch in said circuit ope ative at one of its two positions to connect one selecting branch circuit and the regulating branch circuits for energization and operative at the other of its two positions to'connect the other selecting branch circuit and the regulating branch circuits for energization, a'second switch means in the circuit operable upon movement in opposite directionsand cooperating with the double throw switch in either of its two selected positions to complete circuits through the regulating branches in the same sequence, and a thermostat responsive to the temperature of the air to be conditioned for operating thesecond switch means in opposite directions to initiate 7. In an air conditioning unit, a heating system having a heating element,a heat operated refrigeration system having a cooling element,-a single source of heat, means for varying the rate at which heat is supplied, movable means for selectively supplying heat from said source to operate the heating system or the heat operated refrigeration system, an electric control circuit having a first branch for operating the movablemeans when energized to select the heating system for operation, a second branch for operating the movable means when energized to select the refrigeration system for operation, and a plurality of tertiary branches for operating the heat varying means in a series of steps to control the rate of operation, a double throw switch in said circuit operative at one of its two positions to connect the first branch and plurality of tertiary branches for energization and operative at the other of its two positions to connect the second branch and plurality of tertiary branches for energization, a second switch means in the circuit having a plurality of contacts and cooperating with the double throw switch to complete a circuit through the plurality of tertiary branches in succession when moved in one direction and complete a circuit through plurality of tertiary branches in succession when moved in the oppo site direction, anda thermostat responsive to the temperature of the air tobe "conditioned for operating the second switch to initiate operation of the selected system and control the rate of operation. 1 -8. In an air conditioning unit, a heating system' having a heating element, a heat operated refrigeration system having a-cooling element,

a blower for circulating air to be conditioned over the heating and cooling elements, an electric control circuit having a. first branch for initiatingoperation of the heating system when a third branch for initiating operation of the blower when energized, a double throw switch in energized, a second branch for initiating. operation of the cooling systemwhen energized, and

said circuit operative at one of its two positions to connect the first branch. for en'ergization and operative at the other of its two positions to connect the second and third branches for energization, a second switch in the circuit and cooperating with the double throw switch to com plete a circuit through the first selected branch when moved in one direction and complete a circuit through the selected second and third branches when moved in the other direction, and a thermostat responsive to the temperature of the air to be conditioned for operating the second switch to initiate operation of the selected system.

9.- In an air conditioning unit, a heating system having a heating element, a heat operated refrigeration system having a cooling element, a blower for circulating air to be conditioned over the heating and cooling elements, an electric control circuit having a first branch for initiating operation of the heating system when energized, a second branch for initiating opera tion of the cooling system when energized, and a third branch for initiating operation of the blower when energized, a double throw switch in said circuit operative at one of its two positions to connect the first branch for energization and operative at the other of its two positions to connect the second and third branches for energization, a second switch in the circuit and cooperating with the double throw switch to complete a circuit through the selected first branch when moved in one direction and complete a circuit through the selected second and third branches when moved in the other direction, a thermostat responsive to the temperature of the air to be conditioned for operating the second switch to initiate operation of the selected system, and a circuit for initiating operation of the blower independently of the first two switches including a thermostatically operated switch responsive to the temperature of the heating element to delay operation of the blower until the heating element is hot when the heating system is selected for operation.

10. In an air conditioning unit, a heating system having a heating element, a heat operated refrigeration system having a heating chamber and a cooling element, means for circulating coolmg water through the heat operated refrigeration system, an electric control circuit having a first branch for initiating operation of the heating system when energized, a second branch for initiating operation of the refrigeration system when energized, and a third branch for controlling the supply of cooling water to the refrigeration system, a double throw switch in said circuit operative at one of its two positions to connect the first branch for energization and operative at the other of its two positions to connect the second branch for energization, a second switch in the circuit and cooperating with the double throw switch to complete a circuit through the first selected branch when moved in one direction and complete a circuit through the second selected branch when moved in the other direction, a thermostat responsive to the temperature of the air to be conditioned for operating, the second switch to initiate operation of the selected system, and a thermostatically operated switch responsive to the temperature in the heating chamber of the refrigeration systun to energize the third branch of the circuit independently of the first two switches to delay the supply of cooling water to the refrigeration system until heat has been supplied thereto.

11. In an air conditioning unit, a heating system having a heating element, a heat operated refrigeration system having a heating chamber and a cooling element, a cooling tower for supplying cooling water to the refrigeration system, said cooling tower having operating elements for cooling the water and delivering the cooled water to the refrigeration system, an electric control circuit having a first branch for initiating operation of the heating system when energized, a second branch for initiating operation of the re frigeration system when energized, and a third branch for initiating operation of the cooling tower when energized, a double throw switch in said circuit operative at one of its two positions to connect the first branch for energization and operative at the other of its two positions to connect the second branch for energization, a secoperated switch responsive to the temperature in the heating chamber of the refrigeration system to energize the third branch of the circuit independently of the first two switches to delay operation of the cooling tower until heat has been supplied to the refrigeration system,

12. In an air conditioning system comprising heat exchange means, a blower for flowing air to be conditioned over said heat exchange means, a source of heat, selective control means for adjusting the system for operation by heat from said source to supply either a heating medium or a cooling medium to said heat exchange means, apparatus for removing heat from the system when the latter is adjusted for supplying cooling medium to the heat exchange means, and a thermostatic device 'for delaying operation of both the blower and said heat removing apparatus, respectively, under supervision of said selective control means.

SVEN W. E. ANDERSSON.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED ST ATES PA'I'E'NTB 1 

